Field of the Invention
The present invention relates to a system to detect inputted improper data, a system control method, and a storage medium.
Description of the Related Art
There has been provided a data conversion service on a server that receives an input data such as document data or image data from a service user, converts the data to printing data, and outputs it to a printing device. The data converting service may receive improper data, from a user that generates error in the service. There are 2 types of improper data. One is data that causes an abnormal end of the system during the data conversion processing and another is data that generates a timeout, for example, by entering an infinite loop. Since the abnormal end and the timeout are caused by the unexpected improper data, they are difficult to prevent. However if an error occurs in the system, the system cannot receive next data until the system recovers. If the system is intentionally attacked by inputting the improper data continuously, other users of the service cannot use the data conversion service. In order to prevent such a situation, the server system must ensure a safety.
Here, a method having a standby system is given as an example of a method for ensuring the safety of the system. In a system including only one data conversion unit, the capability of the entire system becomes low due to the retention of the pending data conversion request. Regarding this event, Japanese Patent Laid-Open No. H5-284178 provides a system that improves the capability of the entire system by arranging a plurality of the data conversion units and distributing the pending data conversion requests uniformly at each of the data conversion units. Even in the data conversion service of the above mentioned server, this corresponds to the input of the improper data from the user by multiplexing the data conversion units and providing the system with redundancy.
Generally, after inputting the input data, the user tends to input the same data continuously when there is no reply from the system in predetermined time. When the data inputted by the user was improper data, the user would continuously input the improper data to the system without realizing that the inputted data has generated an error in a part of the multiplexed system. In the data conversion service of the Japanese Patent Laid-Open No. H5-284178, multiplexing the system is performed in correspondence to the improper data. However, the data conversion service was occupied by the continuous input of the improper data by a non-malicious user, and during that time, the other service users could not use the service temporarily.